Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$33.48	5.860%	$35.4419	$35.44	$35.45	$35.40
Purchase #2	$74.88	7.778%	$80.7042	$80.70	$80.70	$80.70
Purchase #3	$236.68	3.111%	$244.0431	$244.04	$244.05	$244.00
Purchase #4	$102.52	6.608%	$109.2945	$109.29	$109.30	$109.30
Purchase #5	$236.72	7.420%	$254.2846	$254.28	$254.30	$254.30
Purchase #6	$164.67	4.860%	$172.673	$172.67	$172.65	$172.70
Purchase #7	$213.76	8.266%	$231.4294	$231.43	$231.45	$231.40
7 purchase totals =	$1,062.71		$1,127.8707	$1,127.85	$1,127.90	$1,127.80